SSIS Error Code DTS_E_CANNOTINSERTNULL: Attempted to insert a null value into a column

 The error code DTS_E_CANNOTINSERTNULL indicates that there is an attempt to insert a NULL value into a column that does not allow NULL values. This typically happens when the SSIS package processes data and encounters a NULL value that it tries to insert into a non-nullable column in the destination.

Steps to Diagnose and Resolve the Issue

1. Identify the Affected Column:

   • Review the detailed error message to identify the column that is causing the issue. The error message should specify which column cannot accept NULL values.

2. Check Source Data:

   • Inspect the source data to determine if there are NULL values in the column that maps to the non-nullable destination column.

3. Add Data Cleansing Logic:

   • Add transformations in your SSIS package to handle NULL values before they are inserted into the destination.

4. Update Destination Column:

   • If appropriate, modify the destination table schema to allow NULL values for the affected column. This should be done with caution and based on the business requirements.

5. Use Default Values:

   • Assign default values to columns when NULL values are encountered, using transformations like Derived Column.

Example Scenario and Solutions

Scenario: A column in the source data contains NULL values, but the corresponding column in the destination table is defined as NOT NULL.

Solutions:

1. Using Derived Column Transformation:

   • Use a Derived Column transformation to replace NULL values with a default value before inserting into the destination table.

   ISNULL([SourceColumn]) ? "DefaultValue" : [SourceColumn]

2. Using Data Conversion Transformation:

   • Convert NULL values to a suitable default value using a Data Conversion transformation.

3. Handling Nulls in SQL Query:

   • If the source is a database, modify the SQL query to handle NULL values before they are fetched by the SSIS package.

   SELECT ISNULL(SourceColumn, 'DefaultValue') AS SourceColumn
   FROM SourceTable
   

Example SSIS Package Configuration

1. Add a Derived Column Transformation:

   • Drag a Derived Column transformation onto the Data Flow task.
   • Configure the Derived Column transformation to replace NULL values with a default value.

   [DerivedColumn] = ISNULL([SourceColumn]) ? "DefaultValue" : [SourceColumn]

2. Update the Data Flow:

   • Ensure that the data flow path includes the Derived Column transformation before reaching the destination component.

Sample Package Configuration

1. Data Flow Task:
   • Source Component: OLE DB Source
   • Transformation: Derived Column
     • Derived Column Name: ReplacedColumn
     • Expression: ISNULL([SourceColumn]) ? "DefaultValue" : [SourceColumn]
   • Destination Component: OLE DB Destination
     • Map ReplacedColumn to the non-nullable column in the destination table

Example SQL Query

If your source is an SQL table, you can handle NULLs directly in your query:

SELECT 
    ISNULL(SourceColumn, 'DefaultValue') AS SourceColumn
FROM 
    SourceTable

By handling NULL values appropriately in your SSIS package, you can prevent the DTS_E_CANNOTINSERTNULL error and ensure smooth data flow into your destination.